ceph-volume util add a helper to check if a device is mounted

Signed-off-by: Alfredo Deza <adeza@redhat.com>

src/ceph-volume/ceph_volume/util/system.py

@@ -1,10 +1,27 @@
 import errno
 import os
 import pwd
+import platform
 import uuid
 from ceph_volume import process
 
 
+# TODO: get these out of here and into a common area for others to consume
+if platform.system() == 'FreeBSD':
+    FREEBSD = True
+    DEFAULT_FS_TYPE = 'zfs'
+    PROCDIR = '/compat/linux/proc'
+    # FreeBSD does not have blockdevices any more
+    BLOCKDIR = '/dev'
+    ROOTGROUP = 'wheel'
+else:
+    FREEBSD = False
+    DEFAULT_FS_TYPE = 'xfs'
+    PROCDIR = '/proc'
+    BLOCKDIR = '/sys/block'
+    ROOTGROUP = 'root'
+
+
 def generate_uuid():
     return str(uuid.uuid4())
 
@@ -48,3 +65,39 @@ def chown(path, recursive=True):
         process.run(['chown', '-R', 'ceph:ceph', path])
     else:
         os.chown(path, uid, gid)
+
+
+def is_mounted(source, destination=None):
+    """
+    Check if the given device is mounted, optionally validating destination.
+    This relies on absolute path devices, it will ignore non-absolute
+    entries like::
+
+        tmpfs /run tmpfs rw,seclabel,nosuid,nodev,mode=755 0 0
+
+    But will parse paths that are absolute like::
+
+        /dev/sdc2 /boot xfs rw,attr2,inode64,noquota 0 0
+
+    When destination is passed in, it will check that the entry where the
+    source appears is mounted to where destination defines. This is useful so
+    that an error message can report that a source is not mounted at an
+    expected destination.
+    """
+    dev = os.path.realpath(source)
+    with open(PROCDIR + '/mounts', 'rb') as proc_mounts:
+        for line in proc_mounts:
+            fields = line.split()
+            if len(fields) < 3:
+                continue
+            mounted_device = fields[0]
+            mounted_path = fields[1]
+            if os.path.isabs(mounted_device) and os.path.exists(mounted_device):
+                mounted_device = os.path.realpath(mounted_device)
+                if mounted_device == dev:
+                    if destination:
+                        destination = os.path.realpath(destination)
+                        return destination == os.path.realpath(mounted_path)
+                    else:
+                        return True
+    return False